The present invention relates to a display device, and more specifically to a liquid crystal display device of a lateral electric field drive mode including a high definition screen.
A liquid crystal display device includes a TFT substrate on which pixels having a pixel electrode, a thin film transistor (TFT), and the like are formed in a matrix configuration, a counter substrate disposed opposite to the TFT substrate, and liquid crystals sandwiched between the TFT substrate and the counter substrate. The optical transmittance of liquid crystal molecules is controlled for the individual pixels, and images are formed. Since the liquid crystal display device is flat and light in weight, the use of the liquid crystal display device is increasing in various fields. A small-sized liquid crystal display device is widely used in a mobile telephone, a DSC (Digital Still Camera), and the like.
In the liquid crystal display device, viewing angle characteristics are a problem. The viewing angle characteristics are phenomena that the luminance is changed or the chromaticity is changed between the case where the screen is viewed from the front and the case where the screen is viewed from the oblique direction. As for the viewing angle characteristics, an IPS (In Plane Switching) mode has more excellent characteristics in which liquid crystal molecules are operated with a horizontal electric field. In the IPS mode, when a region having a different rotation of liquid crystal molecules, a so-called domain, is produced in a pixel, the transmittance and the like are adversely affected. Japanese Unexamined Patent Application Publication No. 2010-128113 describes the shape of a pixel electrode that can suppress the occurrence of such a domain.
On the other hand, for a medium- or small-sized liquid crystal display device, it is strongly demanded to provide a high definition screen. In this case, since a pixel becomes small, the influence of the capacitance between a picture signal line and the pixel is easily increased. Japanese Unexamined Patent Application Publication No. 2001-281682 describes a configuration for measures against display unevenness caused by the difference in capacitances between a pixel electrode and picture signal lines on the left side and the right side of the pixel.